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Message-ID: <5073673C.10905@archidevsys.co.nz>
Date: Tue, 09 Oct 2012 12:52:28 +1300
From: Gavin Flower <GavinFlower@archidevsys.co.nz>
Organization: ArchiDevSys
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To: Craig James <cjames@emolecules.com>
CC: pgsql-performance@postgresql.org
Subject: Re: Two identical systems, radically different performance
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On 09/10/12 12:40, Craig James wrote:
> Nobody has commented on the hyperthreading question yet ... does it 
> really matter? The old (fast) server has hyperthreading disabled, and 
> the new (slower) server has hyperthreads enabled.
>
> If hyperthreading is definitely NOT an issue, it will save me a trip 
> to the co-lo facility.
>
> Thanks,
> Craig
>
> On Mon, Oct 8, 2012 at 3:29 PM, Craig James <cjames@emolecules.com 
> <mailto:cjames@emolecules.com>> wrote:
>
>     One mistake in my descriptions...
>
>     On Mon, Oct 8, 2012 at 2:45 PM, Craig James <cjames@emolecules.com
>     <mailto:cjames@emolecules.com>> wrote:
>
>         This is driving me crazy.  A new server, virtually identical
>         to an old one, has 50% of the performance with pgbench.  I've
>         checked everything I can think of.
>
>         The setups (call the servers "old" and "new"):
>
>         old: 2 x 4-core Intel Xeon E5620
>         new: 4 x 4-core Intel Xeon E5606
>
>
>     Actually it's not 16 cores.  It's 8 cores, hyperthreaded.
>     Hyperthreading is disabled on the old system.
>
>     Is that enough to make this radical difference?  (The server is at
>     a co-location site, so I have to go down there to boot into the
>     BIOS and disable hyperthreading.)
>
>     Craig
>
>
My latest development box (Intel Latest Core i7 3770K Ivy Bridge Quad 
Core with HT 3.4GHz) has hyperthreading - and it *_does_* make a 
significant difference.

Cheers,
Gavin

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    <div class="moz-cite-prefix">On 09/10/12 12:40, Craig James wrote:<br>
    </div>
    <blockquote
cite="mid:CAFwQ8rcyCKcoeEn62_QHMRSmJM03ULERtW6_R=3TaO0twOEV9A@mail.gmail.com"
      type="cite">Nobody has commented on the hyperthreading question
      yet ... does it really matter? The old (fast) server has
      hyperthreading disabled, and the new (slower) server has
      hyperthreads enabled.<br>
      <br>
      If hyperthreading is definitely NOT an issue, it will save me a
      trip to the co-lo facility.<br>
      <br>
      Thanks,<br>
      Craig<br>
      <br>
      <div class="gmail_quote">On Mon, Oct 8, 2012 at 3:29 PM, Craig
        James <span dir="ltr">&lt;<a moz-do-not-send="true"
            href="mailto:cjames@emolecules.com" target="_blank">cjames@emolecules.com</a>&gt;</span>
        wrote:<br>
        <blockquote class="gmail_quote" style="margin:0 0 0
          .8ex;border-left:1px #ccc solid;padding-left:1ex">
          One mistake in my descriptions...<br>
          <br>
          <div class="gmail_quote">On Mon, Oct 8, 2012 at 2:45 PM, Craig
            James <span dir="ltr">&lt;<a moz-do-not-send="true"
                href="mailto:cjames@emolecules.com" target="_blank">cjames@emolecules.com</a>&gt;</span>
            wrote:<br>
            <blockquote class="gmail_quote" style="margin:0 0 0
              .8ex;border-left:1px #ccc solid;padding-left:1ex">This is
              driving me crazy. &nbsp;A new server, virtually identical to an
              old one, has 50% of the performance with pgbench. &nbsp;I've
              checked everything I can think of.<br>
              <br>
              The setups (call the servers "old" and "new"):<br>
              <br>
              old: 2 x 4-core Intel Xeon E5620<br>
              new: 4 x 4-core Intel Xeon E5606<br>
            </blockquote>
            <div><br>
              Actually it's not 16 cores.&nbsp; It's 8 cores, hyperthreaded.&nbsp;
              Hyperthreading is disabled on the old system.<br>
              <br>
              Is that enough to make this radical difference?&nbsp; (The
              server is at a co-location site, so I have to go down
              there to boot into the BIOS and disable hyperthreading.)<br>
              <br>
              Craig<br>
            </div>
          </div>
        </blockquote>
      </div>
      <br>
    </blockquote>
    My latest development box (Intel Latest Core i7 3770K Ivy Bridge
    Quad Core with HT 3.4GHz) has hyperthreading - and it <b><u>does</u></b>
    make a significant difference.<br>
    <br>
    Cheers,<br>
    Gavin<br>
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